While the Flow Cytometry Laboratory functions as a core for the scientific mission of the laboratories located within the NIA Intramural Research Program in Baltimore, several investigators, laboratory groups, or projects accounts for a significant portion of FY2009 resources. Usage by the Laboratory of Immunology (LI;Taub, Weng, Sen) varies between 60-70% of sorting and 50-70% of non-sorting (analytical) capacities, focusing on human and animal (mouse) models of immune status, immunoregulation, immunosuppression, and their relation to development and aging. Other supported projects involve those from the Laboratory of Cardiovascular Sciences (LCS: Boheler, ES cells and cardiomyocte differentiation;Xiao, reporter gene expression), Laboratory of Genetics (LG: Ko, patterns of ES development), Laboratory of Neuroscience (LNS: Mattson, reporter gene expression in neural stem cells and neurogenesis), Laboratory of Clinical Investigation (Bernier), Laboratory of Molecular Gerontology (LMG: Gearhart, antibody diversity and somatic hypermuations), and Laboratory of Cellular and Molecular Biology (LCMB;multiparameter cell cycle analysis). While the lab does not require co authorship on all publications for which we generate data, the following list, in addition to the bibliography below, documents publications from the IRP that include contributions from our core for this reporting period. Nguyen H, Weng NP. (2010) IL-21 preferentially enhances IL-15-mediated homeostatic proliferation of human CD28+ CD8 memory T cells throughout the adult age span. J Leukoc Biol 87:43-9. Aggarwal M, Sommers JA, Shoemaker RH, Brosh RM Jr. (2011) Inhibition of helicase activity by a small molecule impairs Werner syndrome helicase (WRN) function in the cellular response to DNA damage or replication stress.Proc Natl Acad Sci U S A. 1081525-30. Aggarwal M, Sommers JA, Morris C, Brosh RM Jr. (2010) Delineation of WRN helicase function with EXO1 in the replicational stress response. DNA Repair 9:765-76. Yu Q, Sharma A, Ghosh A, Sen JM. (2011) T cell factor-1 negatively regulates expression of IL-17 family of cytokines and protects mice from experimental autoimmune encephalomyelitis. J Immunol. 186:3946-52. Fiori J, Sanghvi M, O'Connell M, Krzysik-Walker S, Moaddel R, Bernier M. (2011). The cannabinoid receptor inverse agonist AM251 regulates expression of EGF receptor and its ligands via destabilization of estrogen-related receptor (ERR) &#945;protein. Br J Parmacol. Mar 30. doi: 10.1111/j.1476-5381.2011.01384.x. Epub ahead of print Maul RW, Saribasak H, Martomo SA, McClure RL, Yang W, Vaisman A, Gramlich HS, Schatz DG, Woodgate R, Wilson DM 3rd, Gearhart PJ. (2011) Uracil residues dependent on the deaminase AID in immunoglobulin gene variable and switch regions.Nat Immunol. 12(1):70-6.